The only model train specialty store I can remember going to is George's Trains in Markham (not easy to transit to)
There are various hobby model stores dotted here and there which feature model figures, model cars, model boats and planes and other things in addition to model trains.
Anime stores there are a bunch. Easiest one to get to might be Animax in Chinatown/Kensington Market area. If authenticity of products doesn't matter as much Pacific Mall might have stuff, but it's been years since I've been there last.
I can't remember any spots to entertain your old electronics and numismatist hobbies. Maybe others can help.